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Biomedical subjects

L C Baker

Publications and source records attributed to L C Baker.

At least 19 recordsLinked to original sources
PubMed2001

The impact of practice setting on physician perceptions of the quality of practice and patient care in the managed care era.

BACKGROUND: Managed care is practiced in both traditional institutional health maintenance organization (HMO) settings and in a variety of complex and decentralized office-based arrangements. This study examines how practice setting affects physician perceptions of the quality of professional practice and patient care in a managed care environment. PARTICIPANTS AND METHODS: A survey was conducted in 1998 of 1081 physicians in San Mateo County, California, who practice in either a traditional staff group model HMO (SGM-HMO) (n = 113) or office-based independent practice (OBIP) (n = 250). Respondents were surveyed about current and past practice characteristics, income changes, current satisfaction with professional and patient care matters, utility of treatment guidelines and formularies, and general perceptions of managed care. Responses were compared between practice settings using bivariate comparisons and logistic regression analyses. RESULTS: Physicians in the SGM-HMO and those in OBIP reported similar hours worked per week, time spent with patients during office visits, and total patient encounters per week. Declining income was more frequent in OBIP (61% vs 47%) and relatively more substantial (27% with income declines >25% vs 4% in SGM-HMO). Adjusting for income changes, practice setting, years in practice, and sex, SGM-HMO physicians were significantly more satisfied with a variety of professional and quality of care issues (P<.001), viewed more favorably the utility of treatment guidelines and drug formularies (P<.001), and held more positive general perceptions of managed care (P<.001) than OBIP physicians. CONCLUSIONS: In a managed care environment, SGM-HMO physicians are significantly more satisfied with the quality of practice and patient care than physicians in OBIP. This study suggests that the myriad managed care contracts, formularies, and guidelines received by physicians in OBIPs may lead to more negative perceptions of the quality of professional practice and patient care.

Attitude of Health Personnel↗
PubMed2001

Managed care and technology adoption in health care: evidence from magnetic resonance imaging.

This paper empirically examines the relationship between HMO market share and the diffusion of magnetic resonance imaging (MRI) equipment. Across markets, increases in HMO market share are associated with slower diffusion of MRI into hospitals between 1983 and 1993, and with substantially lower overall MRI availability in the mid- and later 1990s. High managed care areas also had markedly lower rates of MRI procedure use. These results suggest that technology adoption in health care can respond to changes in financial and other incentives associated with managed care, which may have implications for health care costs and patient welfare.

Catchment Area, Health↗
PubMed2001

Measuring competition in health care markets.

OBJECTIVE: Measuring competition is increasingly important for analysis of health care markets and policies. Measurement of competition in health care is made complex by the breadth of potential issues under study, by the lack of necessary data, and by rapid changes in health care financing and delivery. This study reviews key issues in the measurement of competition and is designed to familiarize researchers and policymakers interested in competition measurement, but not steeped in its practice, with key concepts, data sources, and ways of adapting measures to fit ongoing changes in health care markets. PRINCIPAL FINDINGS: Attention to several key issues will strengthen measurement. Important components of successful measurement are: careful identification of the products and market areas for study; selection of Herfindahl-Hirschman or other indices to fit the issues being considered; consideration of econometric problems, like endogeneity, with common measures; and attention to the ways that current marketplace changes, like growth in managed care, affect the performance of classic measures. Data needed for constructing measures are also frequently scarce, insufficient, or both. Measurement could be improved with access to better data.

Catchment Area, Health↗
PubMed2000

Enhanced dispersion of repolarization and refractoriness in transgenic mouse hearts promotes reentrant ventricular tachycardia.

The heterogeneous distribution of ion channels in ventricular muscle gives rise to spatial variations in action potential (AP) duration (APD) and contributes to the repolarization sequence in healthy hearts. It has been proposed that enhanced dispersion of repolarization may underlie arrhythmias in diseases with markedly different causes. We engineered dominant negative transgenic mice that have prolonged QT intervals and arrhythmias due to the loss of a slowly inactivating K(+) current. Optical techniques are now applied to map APs and investigate the mechanisms underlying these arrhythmias. Hearts from transgenic and control mice were isolated, perfused, stained with di-4-ANEPPS, and paced at multiple sites to optically map APs, activation, and repolarization sequences at baseline and during arrhythmias. Transgenic hearts exhibited a 2-fold prolongation of APD, less shortening (8% versus 40%) of APDs with decreasing cycle length, altered restitution kinetics, and greater gradients of refractoriness from apex to base compared with control hearts. A premature impulse applied at the apex of transgenic hearts produced sustained reentrant ventricular tachycardia (n=14 of 15 hearts) that did not occur with stimulation at the base (n=8) or at any location in control hearts (n=12). In transgenic hearts, premature impulses initiated reentry by encountering functional lines of conduction block caused by enhanced dispersion of refractoriness. Reentrant VT had stable (>30 minutes) alternating long/short APDs associated with long/short cycle lengths and T wave alternans. Thus, optical mapping of genetically engineered mice may help elucidate some electrophysiological mechanisms that underlie arrhythmias and sudden death in human cardiac disorders.

Action Potentials↗
PubMed1999

Association of managed care market share and health expenditures for fee-for-service Medicare patients.

CONTEXT: Managed care has the potential to transform fundamentally the structure and functioning of the entire health care system, including the care provided to patients who are not enrolled in managed care plans. OBJECTIVE: To determine whether increasing health maintenance organization (HMO) market share is associated with decreased expenditures for the care of patients covered by Medicare's traditional fee-for-service plan, a group cared for well outside the boundaries of managed care. DESIGN AND SETTING: Data from the Health Care Financing Administration were used to compare expenditures for the care of Medicare fee-for-service beneficiaries for 802 market areas, representing the entire United States, for 1990 to 1994. These data were matched with data on system-wide (Medicare and non-Medicare) HMO market share in these areas. PATIENTS: All fee-for-service Medicare beneficiaries (1990-1994) except for those with end-stage renal disease. MAIN OUTCOME MEASURE: Average fee-for-service expenditure per fee-for-service Medicare beneficiary by market area. RESULTS: In a regression model, increases in system-wide HMO market share were associated with declines in both Part A and Part B fee-for-service expenditures per Medicare beneficiary (P<.001). Increases from 10% market share to 20% market share were associated with 2.0% decreases in Part A fee-for-service expenditures and 1.5% decreases in Part B fee-for-service expenditures. CONCLUSIONS: Managed care can have widespread effects on the health care system. Health care for individuals who are not covered by managed care organizations can be influenced by the presence of managed care. Lower expenditures in areas with high HMO market shares may indicate that traditional Medicare beneficiaries in areas with high market shares received fewer or less intensive services than traditional Medicare beneficiaries in other areas.

Fee-for-Service Plans↗
PubMed1999

Managed care, consolidation among health care providers, and health care: evidence from mammography.

We discuss the effects of managed care on the structure of the health care delivery system, focusing on managed-care-induced consolidation among health care providers. We empirically investigate the relationship between HMO market share and mammography providers. We find evidence of consolidation: increases in HMO activity are associated with reductions in the number of mammography providers and with increases in the number of services produced by remaining providers. We also find that increases in HMO market share are associated with reductions in costs for mammography and with increases in waiting times for appointments, but not with worse health outcomes.

Adult↗
PubMed1998

Effect of an intensive educational program for minority college students and recent graduates on the probability of acceptance to medical school.

CONTEXT: Increasing the number of minority physicians is a long-standing goal of professional associations and government. OBJECTIVE: To determine the effectiveness of an intensive summer educational program for minority college students and recent graduates on the probability of acceptance to medical school. DESIGN: Nonconcurrent prospective cohort study based on data from medical school applications, Medical College Admission Tests, and the Association of American Medical Colleges Student and Applicant Information Management System. SETTING: Eight US medical schools or consortia of medical schools. PARTICIPANTS: Underrepresented minority (black, Mexican American, mainland Puerto Rican, and American Indian) applicants to US allopathic medical schools in 1997 (N =3830), 1996 (N = 4654), and 1992 (N =3447). INTERVENTION: The Minority Medical Education Program (MMEP), a 6-week, residential summer educational program focused on training in the sciences and improvement of writing, verbal reasoning, studying, test taking, and presentation skills. MAIN OUTCOME MEASURE: Probability of acceptance to at least 1 medical school. RESULTS: In the 1997 medical school application cohort, 223 (49.3%) of 452 MMEP participants were accepted compared with 1406 (41.6%) of 3378 minority nonparticipants (P= .002). Positive and significant program effects were also found in the 1996 (P=.01) and 1992 (P=.005) cohorts and in multivariate analysis after adjusting for nonprogrammatic factors likely to influence acceptance (P<.001). Program effects were also observed in students who participated in the MMEP early in college as well as those who participated later and among those with relatively high as well as low grades and test scores. CONCLUSIONS: The MMEP enhanced the probability of medical school acceptance among its participants. Intensive summer education is a strategy that may help improve diversity in the physician workforce.

Data Collection↗
PubMed1998

Flow cytometric assays to detect platelet activation and aggregation in device-implanted calves.

Cardiovascular device development often relies upon large-animal models to assess blood biocompatibility prior to initiating clinical trials. Unfortunately, the amount of information gleaned from such trials is limited by simple assays that do not take full advantage of immunotechnological advances that increasingly are applied in clinical studies. Thus we have developed and tested new flow cytometric techniques for measuring circulating activated bovine platelets and platelet microaggregates. Monoclonal antibodies (MAbs) raised against both activated and quiescent bovine platelets were incubated with control and PMA-or ADP-stimulated whole blood. Selected MAbs detected activated bovine platelets and platelet microaggregates in vitro with flow cytometry. Five calves implanted with one of two designs of nonpulsatile ventricular-assist devices (VADs) were followed with these assays prior to and during VAD implantation. Circulating activated bovine platelets and microaggregates increased after implantation in all animals and, alternatively, remained elevated or returned toward preimplant levels. Platelet activation percentages as detected temporally by three MAbs were correlated with one another, and platelet activation was correlated with microaggregate formation. In summary, these new methods for the sensitive measurement of circulating activated bovine platelets and microaggregates may provide valuable information for the development and assessment of future cardiovascular device designs.

Adenosine Diphosphate↗
PubMed1998

Assessment of bovine platelet life span with biotinylation and flow cytometry.

Reduced platelet life span is associated with the implantation of a variety of cardiovascular devices and may be used as a gauge of device biocompatibility. In the bovine model, platelet life span has previously been assessed with radioisotope labeling of removed platelets followed by reinjection and periodic gamma counting of blood samples. We report here the use of protein-reactive biotin (sulfo-N-hydroxysuccinimido [NHS]-biotin) as an alternative to radioisotope techniques whereby reinjected biotinylated platelets are subsequently detected in blood samples using phycoerythrin-streptavidin and flow cytometric techniques. Platelet life span was quantified in a normal calf (4.9 days) and in a calf prior to (6.1 days) and following (3.1 days) implantation of a Nimbus Axial Flow Pump ventricular assist device. The assessment of bovine platelet life span with biotinylation and flow cytometry avoids the technical, regulatory, and safety considerations associated with radioisotope usage and appears readily amenable to application in cardiovascular device testing.

Animals↗
PubMed1998

Factors associated with women's adherence to mammography screening guidelines.

OBJECTIVE: To examine individual and environmental factors associated with adherence to mammography screening guidelines. DATA SOURCES: A unique data set that combines a national probability sample (1992 National Health Interview Survey); a national probability sample of mammography facility characteristics (1992 National Survey of Mammography Facilities); county-level data on 1990 HMO market share; and county-level data on the supply of primary care providers (1991 Area Resource File). STUDY DESIGN: The design was cross-sectional. DATA EXTRACTION/ANALYSIS: Data sets were linked to create an individual-level sample of women ages 50-74 (weighted n = 2,026). We used multipart, sequential logistic regression models to examine the predictors of having ever had mammography, having had recent mammography, and adherence to guidelines. We categorized women as adherent if they reported a lifetime number of exams appropriate for their age (based on screening every two years) and they reported having had an exam in the past two years. PRINCIPAL FINDINGS: Only 27 percent of women had the age-appropriate number of screening exams (range 16 percent-37 percent), while 59 percent of women had been screened within two years. Women were significantly more likely to adhere to screening guidelines if they reported participating with their doctor in the decision to be screened; were younger; had smaller families, higher education and income, and a recent Pap smear; reported breast problems; and lived in an area with a higher percentage of mammography facilities with reminder systems, no shortage of primary care providers, higher HMO market share, and higher screening charges. CONCLUSIONS: A small percentage of women adhere to screening guidelines, suggesting that adherence needs to become a focus of clinical, programmatic, and policy efforts.

Aged↗
PubMed1997

The effect of HMOs on fee-for-service health care expenditures: evidence from Medicare.

This paper examines the relationship between HMO market share and fee-for-service health care expenditures using 1986-1990 county- and metropolitan statistical area-level data on Medicare expenditures and HMO market share. Fixed-effects estimates imply that fee-for-service expenditures are concave and decreasing in market share. Increases in market share from 20% to 30% are associated with 3-7% expenditure reductions. Instrumental variable estimates that exploit cross-sectional variation in HMO activity also indicate a concave relationship, with expenditures declining in market share for market shares above 15-18%, but imply larger expenditure responses to market share changes.

Catchment Area, Health↗
PubMed1997

Factors associated with the perception that debt influences physicians' specialty choices.

PURPOSE: To investigate the responses of individual physicians to educational debt. METHOD: Data on 5,175 physicians were taken from the 1991 Robert Wood Johnson Foundation Survey of Young Physicians, a nationally representative survey of physicians under age 45 who had had two to ten years of practice experience as of 1991. The physicians' overall perceptions about the extents to which debt had been an important determinant of specialty choice were explored using multivariate logistic regression analyses. RESULTS: Only 3.2% of the physicians indicated that debt had had a major influence on their specialty choices. About half (56%) of those who felt that debt had been a major influence indicated that they had foregone some training because of their debt levels. Controlling for debt level, the physicians who had had children during medical school and those whose parents had less education and lower incomes were more likely to say that debt had been an influence (p < .05). An examination of the specialties that the physicians reported having foregone because of debt indicated that these physicians had reacted to debt in different ways--some had chosen more specialized fields while others had chosen more generalized fields. CONCLUSION: While the overall effect of debt was small, some individuals were influenced by debt in a variety of ways. Paying attention to the effects of debt on this small population may improve training for some physicians and help better target programs that attempt to influence physicians by alleviating debt.

Adult↗
PubMed1997

Market-level health maintenance organization activity and physician autonomy and satisfaction.

Managed care is widely expected to affect physicians throughout the healthcare system. In this study, we examined the relationship between health maintenance organization (HMO) activity and the level of competition, autonomy, and satisfaction perceived by physicians who do not work for HMOs. We obtained data on physicians from the 1991 Survey of Young Physicians, which contains a nationally representative sample of physicians younger than age 45 who had 2 to 9 years of practice experience in 1991. We examined the relationships between HMO market share and perceived competition, autonomy, and satisfaction using multivariate logistic regression. The main outcome measures were perceived level of competition; several measures of physicians' freedom to undertake common tasks that might be threatened by managed care (e.g., hospitalizing patients, ordering tests and procedures); satisfaction with current practice situation; perceived ability to practice quality medicine; whether the physician would attend medical school again; and satisfaction with medicine as a career. We found that an increase of 10 percentage points in HMO market share was associated with a 28% increase in the probability that physicians will regard their practice situation as very competitive as opposed to somewhat or not competitive (P < 0.01). Examinations of the relationship between HMO market share and autonomy and satisfaction revealed few significant results. We found no evidence that increases in HMO activity adversely affect physician autonomy. Only a limited amount of evidence indicates that increases in HMO activity reduce the satisfaction of specialist physicians, and no evidence associates HMO activity with the satisfaction of generalists. Although physicians perceive HMOs as competitors, HMO activity has not had a strong negative effect on the autonomy and satisfaction of physicians.

Attitude of Health Personnel↗
PubMed1996

Differences in earnings between male and female physicians.

BACKGROUND: Male physicians have long earned more than female physicians, even after differences in the number of hours worked, specialty, practice setting, and other characteristics are taken into account. Whether earnings patterns have changed recently is not known. METHODS: I examined data on earnings from the 1991 Survey of Young Physicians, a nationwide survey of physicians under 45 years of age with two to nine years of practice experience. The results were compared with data from the 1987 Survey of Young Physicians and with data on the earnings of physicians with 10 or more years of experience from the American Medical Association's 1991 Socioeconomic Monitoring System survey. RESULTS: In 1990, young male physicians earned 41 percent more per year than young female physicians (male:female earnings ratio, 1.41; 95 percent confidence interval, 1.34 to 1.49). Per hour, young men earned 14 percent more than young women (ratio, 1.14; 95 percent confidence interval, 1.09 to 1.20). However, after adjusting for differences in specialty, practice setting, and other characteristics, no earnings difference was evident (ratio, 1.00; 95 percent confidence interval, 0.96 to 1.04). In general practice and family practice, women earned more than men, after adjustment for differences in other characteristics (ratio, 0.87; 95 percent confidence interval, 0.78 to 0.97). In internal-medicine subspecialties and emergency medicine, men earned more than women (ratio, 1.26; 95 percent confidence interval, 1.10 to 1.44). Among physicians with 10 or more years of experience, men also earned more than women (ratio, 1.17; 95 percent confidence interval, 1.07 to 1.27). CONCLUSIONS: Young male and female physicians with similar characteristics earn equal amounts of money. However, differences in earnings between men and women remain among older physicians and in some specialties.

Adult↗
PubMed1996

Physician service to the underserved: implications for affirmative action in medical education.

Affirmative action is under increasing scrutiny. In medicine, the observation that minority physicians disproportionately serve minority patients has been one rationale for affirmative action. Using two large physician surveys, we find that minority and women physicians are much more likely to serve minority, poor, and Medicaid populations. Weaker, but significant association exists between physician and patient socioeconomic background. Service patterns are sustained over time and are generally consistent with physician career preferences. Ending affirmative action in medicine may imperil access to care. Results do not support affirmative action based on economic disadvantage instead of race, ethnicity, and sex.

Adult↗
PubMed1995

Tracking the changes in physician practice settings.

OBJECTIVE: To describe the relationships among types of practice settings and physician characteristics and to document changes in these relationships over time. DESIGN: Two national telephone surveys of randomly selected young physicians were conducted in 1987 and 1991. The 1991 survey included reinterviews of 1987 respondents, providing both cohort and repeated cross-sectional data. PARTICIPANTS: The 1987 survey included data on 5312 physicians who had between 2 and 6 years of practice experience and were under age 41 years. The 1991 survey included data on 5002 physicians under age 45 years and in practice between 2 and 10 years, including 2151 reinterviews of 1987 respondents. MAIN OUTCOME MEASURES: Practice settings were classified as traditional, government, group, or managed, based on ownership, practice type, group size, and managed care contracts. RESULTS: Physician sex, race/ethnicity, specialty, and type of medical school were related to the type of practice setting. Young physicians were less likely to practice in traditional settings in 1991 than in 1987 and were more likely to practice in organized practice settings, especially in managed practices. CONCLUSION: Between 1987 and 1991, there was a significant shift away from traditional physician practice settings toward organized practice settings.

Adult↗
PubMed1995

Medical costs in workers' compensation insurance.

We examine whether patients covered by workers' compensation insurance, which covers the cost of medical care for injured workers without cost sharing and with relatively little oversight, are charged more for treatment or receive more services than patients covered by traditional insurance. Our findings indicate that workers compensation recipients are charged more for treatment. This difference persists in individual services--workers' compensation recipients are charged more per X-ray and per examination than our patients. We consider different explanations and argue that price discrimination probably plays a role.

Accidents, Occupational↗